Impact of urbanization on regional extreme precipitation trends observed at China national station network

Abstract

An enhanced extreme precipitation (EXP) in or near cities compared to rural areas has been widely observed and verified in individual urban sites. However, at a sufficiently large region, the robustness of evidence for the urbanization contribution to the estimate of EXP trends is still lacking. Here, we present clear evidence from observational records of a dense national station network that a significant urbanization-induced increase in annual EXP changes across mainland China (p < 0.01), which is detectable through urban‒rural comparative analysis. This urbanization effect accounts for approximately one-third of the observed EXP trends from 1960 to 2018. The results also indicate that urbanization significantly influences the frequency of EXP changes. The positive effect is especially noticeable in the humid climate zones of the southeastern China monsoon region, excluding coastal zones. Our analysis shows that the observed increase in regional EXP is more complex, and the observational data bias related to urbanization has to be considered in the large-scale detection and attribution of extreme precipitation changes.